Currently, an evaporation coater uses a crucible as the evaporation source such that the material can be evaporated directly from the crucible and leave from the gas outlet on the upper end of the crucible. However, during the burn of the material, it often happens that the gas outlet is blocked because of the condensation of the material at the gas outlet. This situation may typically be shown as follows. When confirming the presence of some material in the evaporation source, the evaporation rate thereof may be gradually reduced to zero while the temperature and power is increased continuously. After a while, the accumulated gas in the crucible may increase the internal pressure of the crucible and further burst through the material at the blocked hole. However, when the temperature approaches the alarm temperature before the cracking of the material, if the blocked hole has not been burst through by the material, there is no choice but to decrease the temperature and open the cavity, and then treat the blocked hole manually.
The blocked hole manual treatment method is summarized as: temperature decreasing—cavity opening—processing—vacuum pumping—temperature increasing. It can be seen that this set of procedures must be carried out under the circumstance that the cavity is open and the normal processing of the evaporation coating would be influenced. Furthermore, the whole treatment procedure consumes a long time of at least 4-6 hours, which would greatly influence the service efficiency of the device, and even would result in serious productivity loss. In this method, the blocked hole must be treated under the circumstance that the cavity is open such that the normal processing of the evaporation coating would be influenced, resulting in the problems of long time consuming and low efficiency.